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Old 09-03-2010, 09:00 PM   #48
Scooby Specialist
Member#: 115070
Join Date: May 2006
Chapter/Region: MAIC
Location: Northern VA
2009 DGM LGT Spec.B
08 Audi Q7 4.2 PRM


^You were more right the first time...

There are many builders of performance engines (offshore power boats and racing aviation engines) who say one heat cycle or 5-7 hours of run-in is enough to seat rings. These would be moly and plasma moly types with taper facing. The bore finish is critical and a fine cross hatch is required. For iron or chrome rings a different finish is needed but the time factor is the same.

The bore finish has to be appropriate for the type of rings used, get it wrong and the rings will not seat properly. And getting it wrong has led to a lot of misconceptions about ring seal. Racers don't have 100 miles to break-in motors, just minutes or even less! And aero piston motors run at 75-100% power their entire life! Lycoming test cell break-in procedure says to use full power after 20 minutes of warm up and system checks! They don't use any different ring materials than we are in our motors so why should we use any different procedures to seat rings. Start the motor, warm it up, and run it hard. If it can't survive full throttle and load from mile 0 then it won't survive full throttle after 100, 1,000, or whatever point you decide to stop putting around.

Engines built for hard use and full power for prolonged periods have clear instructions and and procedures and those procedures say to run the engine hard in controlled conditions. There are no fundental differences between those engines and our engines with aftermarket performance internals or even the motors as they come from the factory. My opinion is that the debate has been muddied up by the OEM's and their break-in procedures that are written by legal departments and not engineers. At the same time I would dare to say every car produced in any volume at all is run in hard at the factory. Even if it is only for 10-30 seconds. It's hilarious that we are told to keep it under certain revs and avoid full throttle when they've already done it at the factory!

Enough ranting...
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